At present, facing the complex geological conditions, deep reservoir burial, and high drilling difficulties involved in dense sandstone oil-gas reservoirs, oil-based drilling fluid systems are mainly used for safe and efficient drilling in the process of dense sandstone oil-gas reservoir exploitation. However, oil-based drilling fluids involve high cost and difficulties in disposal of drill cuttings, and can't fully meet the demand for economic and environment-friendly exploitation of dense sandstone oil-gas reservoirs. Hence, there is an urgent need for using water-based drilling fluids to meet the demand for sustainable exploration and development of dense sandstone oil-gas reservoirs. However, conventional water-based drilling fluids currently used can't satisfactorily meet the requirements of drilling and exploitation of dense sandstone oil-gas reservoirs, and have problems mainly in the following aspects.
(1) Hydrate inhibition performance: conventional hydrate inhibitors can't satisfactorily meet the requirements of drilling and exploitation of dense sandstone oil-gas reservoirs, and the inhibition property of water-based drilling fluids can't effectively inhibit dispersion of drill cuttings and protect the particle size distribution in the drilling fluid systems.
(2) Plugging performance: conventional plugging agents can't satisfactorily maintain reasonable particle size distribution in the drilling fluid system, and can't effectively meet the requirements for plugging and mass transfer energy transfer blocking in dense sandstone oil-gas reservoirs and can't stabilize the borehole wall in shale formations.
(3) Lubricating performance: conventional lubricants and their rheological parameters are still incomparable with the properties of oil-based drilling fluids, and can't meet the requirements for efficient lubrication in operation in long horizontal wellbores and surface lubrication of cuttings bed.
Owing to the limitations of well sites (e.g., drilling platforms in remote regions) or the increase of material transportation costs, and the engineering requirements of high-temperature wells in complex structures, there is an increasingly higher demand for a super-amphiphobic strongly self-cleaning high-performance drilling fluid system that can attain a good effect with a small amount of drilling fluid. Therefore, it is urgent to develop a water-based drilling fluid system that can effectively solve the technical problems of high friction resistance, damages to oil-gas reservoir, and borehole collapse encountered in the drilling and exploitation of dense sandstone oil-gas reservoirs.